Multi-ratio transmission

ABSTRACT

A transmission with nine forward and one reverse gear having four planetary gearsets, eight shafts and six shifting elements. The sun gears of gearsets (P 1 , P 3 ) couple shaft ( 5 ), and can couple the housing by brake ( 05 ). Input shaft ( 1 ) can couple, via clutch ( 14 ), shaft ( 4 ), which couples carrier and sun gears of respective gearsets (P 3 , P 2 ) and can couple housing via brake ( 04 ). Shaft ( 1 ) can couple, via clutch ( 17 ), shaft ( 7 ), which couples ring gear of gearset (P 3 ) and can couple, via clutch ( 18 ), shaft ( 8 ) which couples ring gear and carrier of respective gearsets (P 4 , P 2 ). Shaft ( 6 ) couples ring gear and carrier gear of respective gearsets (P 2 , P 4 ). Shaft ( 3 ) couples sun gear of gearset (P 4 ) and can couple, via brake ( 03 ), the housing. Output shaft ( 2 ) couples carrier and ring gear of respective gearsets (P 4 , P 1 ).

This application is a National Stage completion of PCT/EP2013/050352filed Jan. 10, 2013, which claims priority from German patentapplication serial no. 10 2012 202 811.0 filed Feb. 24, 2012.

FIELD OF THE INVENTION

The present invention concerns a multi-ratio transmission of planetarydesign, in particular an automatic transmission for a motor vehicle.

BACKGROUND OF THE INVENTION

According to the prior art, automatic transmissions, in particular formotor vehicles, comprise planetary gearsets which are shifted by meansof frictional or shifting elements such as clutches and brakes, and areusually connected with a starting element which can be operated withslip and is optionally provided with a bridging clutch, such as ahydrodynamic torque converter or a fluid coupling.

Such an automatic transmission is known, for example, from DE 199 12 480B4 by the present applicant. It comprises three single-carrier planetarygearsets as well as three brakes and two clutches for engaging sixforward gears and one reverse gear, a drive input shaft and a driveoutput shaft, wherein the carrier of the first planetary gearset isconnected permanently to the ring gear of the second planetary gearset,the carrier of the second planetary gearset to the ring gear of thethird planetary gearset and the drive input shaft is connected directlyto the sun gear of the second planetary gearset.

Furthermore, in this known transmission it is provided that the driveinput shaft can be connected by the first clutch to the sun gear of thefirst planetary gearset and by the second clutch to the carrier of thefirst planetary gearset, the sun gear of the first planetary gearset canbe connected by the first brake to a housing of the transmission and thecarrier of the first planetary gearset can be connected by the secondbrake to the housing of the transmission, whereas the sun gear of thethird planetary gearset can be connected by the third brake to thehousing of the transmission. The drive output shaft of the transmissionis connected permanently to the carrier of the third planetary gearsetand to the ring gear of the first planetary gearset.

In addition a 9-gear multi-stage transmission is known from DE 29 36 969A1; this comprises eight shifting elements and four planetary gearsets,one planetary gearset serving as the upstream gearset and the maintransmission comprising a Simpson gearset and a further planetarygearset that serves as a reversing gearset.

Other multi-stage transmissions are known, for example, from DE 10 2005010 210 A1 and DE 10 2006 006 637 A1 by the present applicant.

In general, automatically shifted vehicle transmissions of planetarydesign have already been described many times in the prior art and arecontinually undergoing further development and improvement. Thesetransmissions should take up little structural space, in particularrequiring a small number of shifting elements, and in sequentialshifting operations should avoid double shifts, i.e. an engagement ordisengagement of two shifting elements at a time, so that for shiftingoperations in defined gear groups in each case only one shifting elementis changed.

From DE 10 2008 000 428 A1 by the present applicant a multi-stagetransmission of planetary design is known, which comprises a drive inputand a drive output arranged in a housing. In this known transmissionthere are at least four planetary gearsets, denoted in what follows asthe first, second, third and fourth planetary gearsets, at least eightrotating shafts—denoted in what follows as the drive input shaft, thedrive output shaft and the third, fourth, fifth, sixth, seventh andeighth shafts—and at least six shifting elements including brakes andclutches, whose selective engagement produces various gear ratiosbetween the drive input and the drive output, so that preferably nineforward gears and one reverse gear can be produced.

In this case the first and second planetary gearsets, preferablydesigned as minus planetary gearsets, namely ones with a negative fixedtransmission gear ratio, form a shiftable upstream gearset whereas thethird and fourth planetary gearsets form a main gearset.

In this known multi-stage transmission it is provided that the carriersof the first and second planetary gearsets are coupled with one anotherby the fourth shaft, which is connected to an element of the maingearset, the ring gear of the first planetary gearset is coupled to thesun gear of the second planetary gearset by way of the eighth shaft,which can be connected detachably to the drive input shaft by a firstclutch, and the sun gear of the first planetary gearset can be coupledby means of the third shaft, via a first brake, to a housing of thetransmission and can be detachably connected, via a second clutch, tothe drive input shaft, whereas the ring gear of the second planetarygearset can be coupled by means of the fifth shaft, via a second brake,to a housing of the transmission. In addition the seventh shaft ispermanently connected to at least one element of the main gearset andcan be coupled by a third brake to the housing of the transmission,whereas the sixth shaft is permanently connected to at least one furtherelement of the main gearset and can be detachably connected to the driveinput shaft by means of a third clutch; the drive output shaft ispermanently connected to at least one further element of the maingearset.

Preferably, in this known transmission the fourth shaft is permanentlyconnected to the ring gear of the third planetary gearset, whereas thesixth shaft is permanently connected to the ring gear of the fourthplanetary gearset and to the carrier of the third planetary gearset, andcan be detachably connected by the third clutch to the drive inputshaft. Furthermore, the seventh shaft is connected permanently to thesun gears of the third and fourth planetary gearsets and can be coupledby the third brake to a transmission housing. In this case the driveoutput takes place by way of the drive output shaft which is permanentlyconnected to the carrier of the fourth planetary gearset. In addition,the third and fourth planetary gearsets can be combined or reduced to aRavigneaux gearset with a common carrier and a common ring gear.

According to the state of the art, the shifting elements of multi-stagetransmissions designed in that way, which are usually in the form ofdisk clutches or disk brakes, are actuated hydraulically, but thisresults disadvantageously in high hydraulic losses. To avoid theseactuation losses, it would be particularly advantageous to use shiftingelements that can be actuated only as required, for exampleelectro-mechanically actuated shifting elements.

To enable the use of shifting elements that can be actuated as required,the shifting elements, clutches in particular, have to be easilyaccessible from outside.

Shifting elements that can be actuated as required are understood tomean, in particular, ones that need energy only for changing theirshifting condition. This also includes hydraulically actuated shiftingelements whose shifting condition can be maintained by closing a valve.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a multi-stagetransmission of the type mentioned to begin with, comprising nineforward gears and one reverse gear having appropriate gear ratios,wherein the structural complexity, component loading and overall sizeare optimized, and in addition the efficiency in terms of drag lossesand gearing losses is improved. Furthermore the shifting elements of thetransmission should be easily accessible from outside, whereby thefitting of shifting elements that can be actuated as required isfacilitated. Moreover, the transmission should be suitable for bothstandard and also front-transverse mounting designs.

A multi-stage transmission of planetary design according to theinvention is proposed, which comprises a drive input and a drive output.Furthermore, at least four planetary gearsets, called the first, second,third and fourth planetary gearsets in what follows, eight rotatingshafts—called the drive input shaft, the drive output shaft and thethird, fourth, fifth, sixth, seventh and eighth shafts in whatfollows—and six shifting elements, preferably in the form of frictionalshifting elements or interlocking shifting elements, including brakesand clutches, are provided, whose selective engagement produces variousgear ratios between the drive input and the drive output, such thatpreferably nine forward gears and one reverse gear can be obtained.

The planetary gearsets of the transmission are preferably designed asminus planetary gearsets.

As is known, a simple minus planetary gearset has a sun gear, a ringgear and a carrier on which planetary gearwheels are mounted to rotate,and each of the planetary gearwheels meshes with the sun gear and thering gear. Thus, if the carrier is held fixed, the ring gear rotates inthe opposite direction to the sun gear. In contrast a simple plusplanetary gearset has a sun gear, a ring gear and a carrier on whichinner and outer planetary gearwheels are mounted to rotate, such thatall the inner planetary gearwheels mesh with the sun gear and all theouter planetary gearwheels mesh with the ring gear and each innerplanetary gearwheel meshes with a respective outer planetary gearwheel.Accordingly, if the carrier is held fixed, the ring gear rotates in thesame direction as the sun gear and the fixed transmission gear ratio ispositive.

In a preferred embodiment of the invention the sun gear of the firstplanetary gearset is connected to the fifth shaft, which is connected tothe sun gear of the third planetary gearset and can be coupled by athird brake to the housing of the transmission, whereas the drive inputshaft can be detachably connected by a first clutch to the fourth shaft,which is connected to the carrier of the third planetary gearset and tothe sun gear of the second planetary gearset and which can be coupled bya second brake to the transmission housing. In addition, the drive inputshaft can be detachably connected by a second clutch to the seventhshaft, which is connected to the ring gear of the third planetarygearset, whereas the drive input shaft can also be detachably connectedby a third clutch to the eighth shaft, which is connected to ring gearof the fourth planetary gearset and to the carrier of the secondplanetary gearset.

Moreover, the sixth shaft of the transmission is connected to the ringgear of the second planetary gearset and to the carrier of the firstplanetary gearset, whereas the third shaft of the transmission isconnected to the sun gear of the fourth planetary gearset and can becoupled by a first brake to the housing, and whereas the drive outputshaft of the transmission is connected to the carrier of the fourthplanetary gearset and to the ring gear of the first planetary gearset.

In that the first, second and third clutches are arranged on the driveinput shaft and the remaining shifting elements are in the form ofbrakes, it is ensured that all the shifting elements of the transmissioncan be accessed easily, so that the shifting elements can be designed asshifting elements that can be actuated as required. In other embodimentsshifting elements of the transmission can be in the form ofhydraulically actuated shifting elements.

In a further embodiment of the invention, starting with the embodimentjust described the second clutch can be replaced by a fourth clutch,whereby the seventh shaft is connected to the sun gear of the thirdplanetary gearset and the drive input shaft is connected to the ringgear of the third planetary gearset. In this case the fourth clutchdetachably connects the seventh shaft, which is connected to the sungear of the third planetary gearset, to the fifth shaft, which isconnected to the sun gear of the first planetary gearset, to oneanother. According to a further development of this embodiment in thiscase the first clutch can be replaced by a fifth clutch, whichdetachably connects the fourth shaft to the seventh shaft.

The design of the multi-stage transmission in accordance with theinvention ensures that the shifting elements of the transmission areeasily accessible, so that the shifting elements can be designed in theform of shifting elements that can be actuated as required. Moreover,particularly for passenger cars, suitable gear ratios are available andthe multi-stage transmission has a high overall spread, which improvesdriving comfort and reduces fuel consumption significantly.

Furthermore, since the multi-stage transmission according to theinvention has a small number of shifting elements its structuralcomplexity is reduced considerably. Advantageously, with the multi-stagetransmission according to the invention starting can be carried out bymeans of a hydrodynamic converter, an external starting clutch or evenwith other suitable external starting elements. It is also conceivableto enable a starting process with a starting element integrated in thetransmission. Preferably, a starting element which is actuated in thefirst forward gear and the reverse gear is suitable.

Moreover, the efficiency of the multi-stage transmission in the maindriving gears is good in relation to drag and gearing losses.

Advantageously, the torques imposed on the shifting elements andplanetary gearsets of the multi-stage transmission are small, so thatwear in the multi-stage transmission is advantageously reduced.Furthermore, since the torques are small the dimensions of thetransmission components can be made smaller, whereby the fitting spaceand the corresponding costs can be reduced. Moreover the shafts,shifting elements and planetary gearsets also rotate at low speeds.

Besides, the transmission according to the invention is designed in suchmanner as to enable adaptation to various drive-train designs, in termsof both force flow direction and also spatial considerations.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of the invention will be explained in greater detailwith reference to the attached figures, which show:

FIG. 1: A schematic representation of a first preferred embodiment of amulti-stage transmission according to the invention;

FIG. 2: An example shifting scheme for a multi-stage transmission as inFIG. 1,

FIG. 3: A schematic representation of a second preferred embodiment of amulti-stage transmission according to the invention;

FIG. 4: A schematic representation of a further preferred embodiment ofa multi-stage transmission according to the invention;

FIG. 5: An example of a shifting scheme for a multi-stage transmissionas in FIGS. 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a multi-stage transmission according to the inventionhaving a drive input shaft 1, a drive output shaft 2 and four planetarygearsets P1, P2, P3 and P4, which are arranged in a housing G. In theexample shown in FIG. 1 the planetary gearsets P1, P2, P3 and P4 aredesigned as minus planetary gearsets. According to the invention, atleast one of the planetary gearsets P1, P2, P3, P4 can be a plusplanetary gearset if at the same time the carrier and ring gearconnection is exchanged and, compared with the minus planetary gearsetdesign, the value of the fixed transmission ratio is increased by 1.

In the example embodiment shown, as viewed axially P1, P2, P3 P4 arearranged in the sequence P1 (first planetary gearset), P2 (secondplanetary gearset), P3 (third planetary gearset and P4 (fourth planetarygearset). According to the invention, the axial sequence of theindividual planetary gearsets and the arrangement of the shiftingelements can be chosen freely so long as it enables the elements to beconnected appropriately.

As can be seen from FIG. 1, six shifting elements are provided, namelythree brakes 03, 04, 05, and three clutches 14, 17, 18. The spatialarrangement of the shifting elements can be as desired and is restrictedonly by their size and the external shape. The clutches and brakes ofthe transmission are preferably in the form of frictional shiftingelements or disk shifting elements, but they can also be interlockingshifting elements.

With these shifting elements a selective engagement of nine forwardgears and one reverse gear can be obtained. The multi-stage transmissionaccording to the invention has a total of eight rotating shafts, namely1, 2, 3, 4, 5, 6, 7 and 8, of which the drive input shaft is the firstshaft 1 and the drive output shaft is the second shaft 2 of thetransmission.

According to the invention, in the multi-stage transmission of FIG. 1 itis provided that the sun gear of the first planetary gearset P1 isconnected to the fifth shaft 5, which is connected to the sun gear ofthe third planetary gearset P3 and can be coupled by a third brake 05 tothe housing G of the transmission, whereas the drive input shaft 1 canbe detachably connected by a first clutch 14 to the fourth shaft 4,which is connected to the carrier of the third planetary gearset P3 andto the sun gear of the second planetary gearset P2 and which can becoupled to the housing G by a second brake 04. Referring to FIG. 1, thedrive input shaft 1 can be detachably connected by a second clutch 17 tothe seventh shaft 7 which is connected to the ring gear of the thirdplanetary gearset P3 and can be detachably connected by a third clutch18 to the eighth shaft 8, which is connected to the ring gear of thefourth planetary gearset P4 and to the carrier of the second planetarygearset P2.

As can be seen from FIG. 1, the sixth shaft 6 is connected to the ringgear of the second planetary gearset P2 and to the carrier of the firstplanetary gearset P1, whereas the third shaft 3 is connected to the sungear of the fourth planetary gearset P4 and can be coupled to thehousing G by a first brake 03, and whereas the drive output shaft 2 ofthe transmission is connected to the carrier of the fourth planetarygearset P4 and to the ring gear of the first planetary gearset P1.

In this case, as viewed axially the first, second and third clutches 14,17, 18 are preferably arranged next to one another and can be made asdisk shifting elements with a common outer disk carrier. In the exampleembodiment shown the first brake o3 in particular is suitable to be madeas a claw shifting element, whereby the fuel consumption issignificantly improved.

FIG. 2 shows an example shifting scheme for a multi-stage transmissionas in FIG. 1. For each gear three shifting elements are closed. Theshifting scheme shows the respective transmission ratios i of theindividual gear steps and the gear intervals or step intervals φ to thenext-higher gear determined therefrom, the value of the transmission'sspread being 9.008 overall.

The values for the fixed transmission ratios of the planetary gearsetsP1, P2, P3, P4 designed as minus planetary gearsets in the example shownare −3.900, −2.146, −1.634 and −3.045 respectively. FIG. 2 shows that ina sequential shift pattern, in each case only one shifting element hasto be engaged and one shifting element disengaged, since two adjacentgears use two shifting elements together. It can also be seen that alarge spread with small gear intervals is achieved.

The first forward gear is obtained by closing the first and third brakes03, 05 and the second clutch 17, the second forward gear by closing thefirst and third brakes 03, 05 and the first clutch 14, the third forwardgear by closing the first brake 03 and the first and second clutches 14,17, the fourth forward gear by closing the first brake 03 and the firstand third clutches 14, 18, the fifth forward gear, which in the exampleshown is designed to be a direct gear, is obtained by closing the first,second and third clutches 14, 17, 18, the sixth forward gear by closingthe third brake 05 and the first and third clutches 14, 18, the seventhforward gear by closing the third brake 05 and the second and thirdclutches 17, 18, the eighth forward gear by closing the second and thirdbrakes 04, 05 and the third clutch 18, and the ninth forward gear byclosing the second brake 04 and the second and third clutches 17, 18,whereas the reverse gear is obtained by closing the first and secondbrakes 03, 04 and the second clutch 17.

Alternatively the fourth forward gear can be engaged by other shiftcombinations, which are indicated as M is FIG. 2. Thus, the fourthforward gear can be obtained by closing the first and third brakes 03,05 and the third clutch 18, or by closing the first and second brakes03, 04 and the third clutch 18, or by closing the first brake 03 and thesecond and third clutches 17, 18.

Since the first brake 03 and the second clutch 17 are closed in both thefirst forward gear and the reverse gear, these shifting elements can beused as starting elements.

According to the invention, with the same transmission scheme anddepending on the shifting logic, different gear intervals can also beobtained so that application-specific or vehicle-specific variation ispossible.

The example embodiment shown in FIG. 3 corresponds to the exampleembodiment according to FIG. 1, with the differences that the secondclutch 17 is replaced by a fourth clutch 57, the seventh shaft 7 isconnected to the sun gear of the third planetary gearset P3, and thedrive input shaft 1 is connected to the ring gear of the third planetarygearset P3. In this case the fourth clutch 57 detachably connects to oneanother the seventh shaft 7, which is connected to the sun gear of thethird planetary gearset P3, and the fifth shaft 5 which is connected tothe sun gear of the first planetary gearset P1.

In the transmission shown in FIG. 3 the sun gear of the first planetarygearset P1 is connected to the fifth shaft 5, which can be coupled by athird brake 05 to the housing G, whereas the drive input shaft 1 can bedetachably connected by a first clutch 14 to the fourth shaft 4, whichis connected to the carrier of the third planetary gearset P3 and to thesun gear of the second planetary gearset P2 and which can be coupled tothe housing G by a second brake 04. In addition the drive input shaft 1is connected to the ring gear of the third planetary gearset P3 and canbe detachably connected by a third clutch 18 to the eighth shaft 8,which is connected to the ring gear of the fourth planetary gearset P4and to the carrier of the second planetary gearset P2, whereas the sixthshaft 6 is connected to the ring gear of the second planetary gearset P2and to the carrier of the first planetary gearset P1, and the thirdshaft 3 is connected to the sun gear of the fourth planetary gearset P4and can be coupled to the housing C by a first brake 03. Furthermore,the seventh shaft 7 is connected to the sun gear of the third planetarygearset P3 and can be detachably connected by the fourth clutch 57 tothe fifth shaft 5. The drive output shaft 2 is connected to the carrierof the fourth planetary gearset P4 and to the ring gear of the firstplanetary gearset P1.

As viewed axially, the first and third clutches 14, 18 are preferablyarranged next to one another and can be made as disk clutches with acommon outer disk carrier.

The transmission shown in FIG. 4 differs from the example embodimentaccording to FIG. 3 in that the first clutch 14 is replaced by a fifthclutch 47, which detachably connects the fourth shaft 4 to the seventhshaft 7. By closing the first clutch 14 or the fifth clutch 47, thethird planetary gearset P3 is blocked.

The object of FIG. 5 is an example shifting scheme for a mufti-stagetransmission according to FIG. 3. In the example shown, the values forthe fixed transmission ratios of the planetary gearsets P1, P2, P3 P4designed in the form of minus planetary gearsets are −3.900, −2.146,−1.634 and −3.045 respectively.

The first forward gear is obtained by closing the first and third brakes03, 05 and the fourth clutch 57, the second forward gear by closing thefirst and third brakes 03, 05 and the first clutch 14, the third forwardgear by closing the first brake 03 and the first and fourth clutches 14,57, the fourth forward gear by closing the first brake 03 and the firstand third clutches 14, 18, the fifth forward gear, which in the exampleshown is designed to be a direct gear, by closing the first, third andfourth clutches 14, 18, 57, the sixth forward gear by closing the thirdbrake 05 and the first and third clutches 14, 18, the seventh forwardgear by closing the third brake 05 and the third and fourth clutches 18,57, the eighth forward gear by closing the second and third brakes 04,05 and the third clutch 18, and the ninth forward gear is obtained byclosing the second brake 04 and the third and fourth clutches 18, 57,whereas the reverse gear is obtained by closing the first and secondbrakes 03, 04 and the fourth clutch 57.

According to the invention the fourth forward gear can be engaged byother shift combinations, which are indicated as M in FIG. 4. Thus thefourth forward gear can be obtained by closing the first and secondbrakes 03, 04 and the third clutch 18, or by closing the first brake 03and the third and fourth clutches 18, 57, or by closing the first andthird brakes 03, 05 and the third clutch 18.

In the case when as shown in the embodiment according to FIG. 4 thefirst clutch 14 is replaced by a fifth clutch 47 which detachablyconnects the fourth shaft 4 to the seventh shaft 7, then in the shiftingscheme according to FIG. 5 the first clutch 14 is replaced by the fifthclutch 47.

According to the invention, it is also optionally possible to provideadditional freewheels at any suitable point in the multi-stagetransmission, for example between a shaft and the housing or to connecttwo shafts when necessary.

On the drive input side or on the drive output side an axle differentialand/or a transfer box differential can be arranged.

In an advantageous further development of the invention the drive inputshaft 1 can if necessary be separated from a drive engine by a clutchelement, wherein for the clutch element, a hydrodynamic converter, ahydraulic clutch, a dry starting clutch, a wet starting clutch, amagnetic power clutch or a centrifugal force clutch can be used. It isalso possible to arrange such a starting element behind the transmissionin the force flow direction, and in that case the drive input shaft 1 isconnected permanently to the crankshaft of the drive engine.

The multi-stage transmission according to the invention also enables atorsion oscillation damper to be arranged between the drive engine andthe transmission.

In a further embodiment of the invention (not illustrated), it ispossible to arrange on any shaft, preferably on the drive input shaft 1or the drive output shaft 2, a wear-free brake such as a hydraulic orelectric retarder or the like, this being particularly appropriate foruse in commercial vehicles. Furthermore, a power-take-off drive can beprovided on any shaft, preferably on the drive input shaft 1 or thedrive output shaft 2, for driving additional aggregates.

The frictional shifting elements used can be in the form of powershiftclutches or brakes. In particular, friction-locking clutches or brakessuch as disk clutches, band brakes and/or cone clutches can be used.

A further advantage of the multi-stage transmission proposed herein isthat an electric machine can be connected to any shaft as a generatorand/or as an additional drive machine.

INDEXES

-   1 First shaft, drive input shaft-   2 Second shaft, drive output shaft-   3 Third shaft-   4 Fourth shaft-   5 Fifth shaft-   6 Sixth shaft-   7 Seventh shaft-   8 Eighth shaft-   03 First brake-   04 Second brake-   05 Third brake-   14 First clutch-   17 Second clutch-   18 Third clutch-   57 Fourth clutch-   47 Fifth clutch-   G Housing-   P1 First planetary gearset-   P2 Second planetary gearset-   P3 Third planetary gearset-   P4 Fourth planetary gearset-   i Transmission ratio-   φ Gear interval

1-8. (canceled)
 9. An automatic multi-stage transmission of a planetarydesign for a motor vehicle, the multi-stage transmission comprising: adrive input shaft (1) and a drive output shaft (2); first, second, thirdand fourth planetary gearsets (P1, P2, P3, P4) being arranged within ahousing (G), and each of the first planetary gearset (P1), the secondplanetary gearset (P2), the third planetary gearset (P3) and the fourthplanetary gearset (P4) comprises a sun gear, a ring gear and a carrier;third, fourth, fifth, sixth, seventh and eighth rotating shafts (3, 4,5, 6, 7, 8); six shifting elements (03, 04, 05, 14, 17, 18) comprisingfirst, second and third brakes (03, 04, 05) and first, second and thirdclutches (14, 17, 18), and selective engagement of the first, the secondand the third brakes and the first, the second and the third clutchesproducing various transmission ratios between the drive input shaft (1)and the drive output shaft (2) such that nine forward gears and onereverse gear can be implemented; the sun gear of the first planetarygearset (P1) being connected to the fifth shaft (5), which is connectedto the sun gear of the third planetary gearset (P3) and beingconnectable to the housing (G) by the third brake (05); the drive inputshaft (1) being detachably connectable, by the first clutch (14), to thefourth shaft (4), the fourth shaft (4) being connected to the carrier ofthe third planetary gearset (P3) and to the sun gear of the secondplanetary gearset (P2), and the fourth shaft (4) being connectable tothe housing (G) by the second brake (04); the drive input shaft (1)being detachably connectable, by the second clutch (17), to the seventhshaft (7), the seventh shaft (7) being connected to the ring gear of thethird planetary gearset (P3), and the drive input shaft (1) beingdetachably connectable, by the third clutch (18), to the eighth shaft(8) being connected to the ring gear of the fourth planetary gearset(P4) and the carrier of the second planetary gearset (P2); the sixthshaft (6) being connected to the ring gear of the second planetarygearset (P2) and the carrier of the fourth planetary gearset (P4) andthe third shaft (3) being connected to the sun gear of the fourthplanetary gearset (P4) and being connectable, by the first brake (03),to the housing (0); and the drive output shaft (2) being connected tothe carrier of the fourth planetary gearset (P4) and to the ring gear ofthe first planetary gearset (P1).
 10. The multi-stage transmissionaccording to claim 9, wherein the first, the second, the third and thefourth planetary gearsets (P1, P2, P3, P4) are designed as minusplanetary gearsets.
 11. The multi-stage transmission according to claim9, wherein the first, the second, the third and the fourth planetarygearsets (P1, P2, P3, P4), when viewed axially, are arranged in asequential order of the first planetary gearset (P1), the secondplanetary gearset (P2), the third planetary gearset (P3) and the fourthplanetary gearset (P4).
 12. The multi-stage transmission according toclaim 9, wherein the first, the second and the third clutches (14, 17,18), when viewed axially, are arranged adjacent to one another and asdisk shifting elements which have a common outer disk carrier.
 13. Themulti-stage transmission according to claim 9, wherein the six shiftingelements (03, 04, 05, 14, 17, 18) of the multi-stage transmission aredesigned as shifting elements that are independently, selectivelyactuatable.
 14. The multi-stage transmission according to claim 9,wherein the first brake (03) is an interlocking shifting element. 15.The multi-stage transmission according to claim 9, wherein a firstforward gear is implemented by engagement of the first and the thirdbrakes (03, 05) and the second clutch (17), a second forward gear isimplemented by engagement of the first and the third brakes (03, 05) andthe first clutch (14), a third forward gear is implemented by engagementof the first brake (03) and the first and the second clutches (14, 17),a fourth forward gear is implemented by engagement of the first brake(03), the third clutch (18) and one of the first clutch (14), the secondclutch (17), the second brake (04) and the third brake (05), a fifthforward gear is implemented by engagement of the first, the second andthe third clutches (14, 17, 18), a sixth forward gear is implemented byengagement of the third brake (05) and the first and the third clutches(14, 18), a seventh forward gear is implemented by engagement of thethird brake (05) and the second and the third clutches (17, 18), aneighth forward gear is implemented by engagement of the second and thethird brakes (04, 05) and the third clutch (18), a ninth forward gear isimplemented by engagement of the second brake (04) and the second andthe third clutches (17, 18), and the reverse gear is implemented byengagement of the first and the second brakes (03, 04) and the secondclutch (17).
 16. The multi-stage transmission according to claim 15,wherein the fourth forward gear is implemented by engagement of thefirst brake (03) and the first and the third clutches (14, 18).
 17. Themulti-stage transmission according to claim 15, wherein the fourthforward gear is implemented by engagement of the first and the thirdbrakes (03, 05) and the third clutch (18).
 18. The multi-stagetransmission according to claim 15, wherein the fourth forward gear isimplemented by engagement of the first and the second brakes (03, 04)and the third clutch (18).
 19. The multi-stage transmission according toclaim 15, wherein the fourth forward gear is implemented by engagementof the first brake (03) and the second and the third clutches (17, 18).20. A multi-stage automatic transmission of planetary design for a motorvehicle, the transmission comprises a drive input shaft (1) and a driveoutput shaft (2); first, second, third and fourth planetary gearsets (P1P2, P3, P4) being arranged within a housing (G), each of the firstplanetary gearset (P1), the second planetary gearset (P2), the thirdplanetary gearset (P3) and the fourth planetary gearset (P4) comprises asun gear, a ring gear and a carrier; third, fourth, fifth, sixth,seventh and eighth rotating shafts (3, 4, 5, 6, 7, 8); first, second andthird brakes (03, 04, 05) and first, second and third clutches (14, 17,18), selective engagement of the first, the second and the third brakesand the first, the second and the third clutches producing varioustransmission ratios between the drive input shaft (1) and the driveoutput shaft (2) such that nine forward gears and one reverse gear canbe implemented; the drive input shaft (1) being connectable to thefourth shaft (4) via the first clutch (14); the drive input shaft (1)being connectable to the seventh shaft (7) via the second clutch (17);the drive input shaft (1) being connectable to the eighth shaft (8) viathe third clutch (18); the drive output shaft (2) being continuouslyconnected to the carrier of the fourth planetary gearset (P4) and thering gear of the first planetary gearset (P1); the third shaft (3) beingcontinuously connected to the sun gear of the fourth planetary gearset(P4) and being connectable, via the first brake (03), to the housing(G); the fourth shaft (4) being continuously connected to the carrier ofthe third planetary gearset (P3) and the sun gear of the secondplanetary gearset (P2) and being connectable, via the second brake (04),to the housing (G); the fifth shaft (5) being continuously connected tothe sun gear of the first planetary gearset (P1) and the sun gear of thethird planetary gearset (P3) and being connectable, via the third brake(05), to the housing (G); the sixth shaft (6) being continuouslyconnected to the ring gear of the second planetary gearset (P2) and thecarrier of the first planetary gearset (P1); the seventh shaft (7) beingcontinuously connected to the ring gear of the third planetary gearset(P3); and the eighth shaft (8) being continuously connected to the ringgear of the fourth planetary gearset (P4) and the carrier of the secondplanetary gearset (P2).
 21. The multi-stage transmission according toclaim 20, wherein a first forward gear is implemented by engagement ofthe first and the third brakes (03, 05) and the second clutch (17), asecond forward gear is implemented by engagement of the first and thethird brakes (03, 05) and the first clutch (14), a third forward gear isimplemented by engagement of the first brake (03) and the first and thesecond clutches (14, 17), a fourth forward gear is implemented byengagement of the first brake (03), the third clutch (18) and one of thefirst clutch (14), the second clutch (17), the second brake (04) and thethird brake (05), a fifth forward gear is implemented by engagement ofthe first, the second and the third clutches (14, 17, 18), a sixthforward gear is implemented by engagement of the third brake (05) andthe first and the third clutches (14, 18), a seventh forward gear isimplemented by engagement of the third brake (05) and the second and thethird clutches (17, 18), an eighth forward gear is implemented byengagement of the second and the third brakes (04, 05) and the thirdclutch (18), a ninth forward gear is implemented by engagement of thesecond brake (04) and the second and the third clutches (17, 18), andthe reverse gear is implemented by engagement of the first and thesecond brakes (03, 04) and the second clutch (17).
 22. The multi-stagetransmission according to claim 21, wherein the fourth forward gear isimplemented by engagement of the first brake (03) and the first and thethird clutches (14, 18).
 23. The multi-stage transmission according toclaim 21, wherein the fourth forward gear is implemented by engagementof the first and the third brakes (03, 05) and the third clutch (18).24. The multi-stage transmission according to claim 21, wherein thefourth forward gear is implemented by engagement of the first and thesecond brakes (03, 04) and the third clutch (18).
 25. The multi-stagetransmission according to claim 21, wherein the fourth forward gear isimplemented by engagement of the first brake (03) and the second and thethird clutches (17, 18).